At 03:36 PM 15-03-98 -0700, you wrote: >1) The material is called Polymethyl Methacrylite and is available from the >manufacturer in cylinders up to 10 ft in diam. Sounds better than a dome. Here is a link to a sub that uses a cylinder of acrylic. http://www.ove.fr/~stephane/bs_photos.html#2 It seems a much simpler way to make a sub with large viewing areas. Dave Everett